Perhaps optimism must take on some form of vagueness. As apposed to saying "this will happen at such and such a time" perhaps we should say "this will happen, I know it". For the coming Kingdom of God, every follower of Christ has the hope of good triumphing over evil, righteousness prevailing corruption and truth conquering the lie. We don't know when exactly it's going to happen and it's not 100% clear how it's going to happen, we just know it. It's going to happen.